Conventionally, in order to achieve a high level of automated operation in a plant, a factory, or the like, a distributed control system (DSC) is implemented, in which on-site devices (measuring devices and actuator devices) referred to as field devices are connected via a communication means to a control apparatus that controls the field devices. Although the communication system that forms the base of such a distributed control system had been almost always one that communicates by cable, recent years have seen the appearance of ones that communicate wirelessly, in conformance with an industrial wireless communication standard such as ISA100.11a or WirelessHART (registered trademark).
For example, a communication system conforming to the above-noted ISA100.11a generally is constituted by a field devices capable of wireless communication (wireless field devices), a gateway device capable of wireless communication (wireless gateway device), and a management apparatus. The wireless gateway device forms a wireless communication network between the wireless gateway device and wireless field devices. The wireless gateway device, in addition to controlling the operation of wireless field devices that have joined the wireless communication network, performs tasks such as collecting various data obtained by the wireless field devices. The management apparatus is connected to the wireless gateway device via a communication line. The management apparatus manages the wireless field devices via the wireless gateway device.
Patent Reference 1 noted below discloses art for preventing faulty operation of terminals, even when there is a mixture of old terminals operating in accordance with an old protocol and new terminals adopting a new protocol in communication system such as a third-generation mobile communication system. The art disclosed in Patent Reference 1 does not communicate in conformance with the above-noted industrial wireless communication standard. Specifically, in Patent Reference 1, if a control signal is sent to another terminal, the control signal that is to be transmitted is intentionally changed (processed to cause an error), so that a specific error occurs in the other terminal, which is an existing terminal. In Patent Reference 1, this prevents faulty operation in both an old terminal and a new terminal.